class_docstr: Method that greedily adds sentences to a summary so long as it decreases the
  KL Divergence.
  Source: http://www.aclweb.org/anthology/N09-1041
class_docstr_tok: ["Method","that","greedily","adds","sentences","to","a","summary","so","long","as","it","decreases","the","KL","Divergence",".","Source",":","http",":","\/\/www.aclweb.org\/anthology\/N09-1041"]
code: def _joint_freq(self, word_list_1, word_list_2):
      # combined length of the word lists
      total_len = len(word_list_1) + len(word_list_2)
  
      # word frequencies within each list
      wc1 = self._compute_word_freq(word_list_1)
      wc2 = self._compute_word_freq(word_list_2)
  
      # inputs the counts from the first list
      joint = wc1.copy()
  
      # adds in the counts of the second list
      for k in wc2:
          if k in joint:
              joint[k] += wc2[k]
          else:
              joint[k] = wc2[k]
  
      # divides total counts by the combined length
      for k in joint:
          joint[k] /= float(total_len)
  
      return joint
  
file_path: sumy/sumy/summarizers/kl.py
imports: from __future__ import absolute_import
  from __future__ import division, print_function, unicode_literals
  import math
  from ._summarizer import AbstractSummarizer
label_desc: Use image node_id 9 for calling the KLSummarizer obj's underlying member method code with example usage: obj._joint_freq(word_list_1, word_list_2) and returns: joint